With conventional ink jet printers, drops of liquid ink are ejected onto a printer paper sheet for recording. An ink container for holding the ink must satisfy several requirements. The ink must not leak during vibrations or impacts in order not to contaminate the surrounding environment. The structure must substantially prevent evaporation of ink components to keep constant the physical characteristic of the ink, such as the surface tension and viscosity. An alarm must be generated for signaling the need for supplementing the ink when there is little ink left in the ink container. For ink jet printers where a voltage is applied as necessary to eject the ink, traditional residual ink detection mechanisms, such as magnetic floats or photosensitive detection, are not effective because the new ink containers are fiat and thin. The measurement readings may be inaccurate because the magnetic float may appear stationary or the volume of the bag may not decrease with gravity. In a first prior art example, J.P.N. 57-187293, Tanaka measures the electrostatic capacity across an ink container as shown in FIG. 1. In a second prior art example shown in FIGS. 2(a)-(d'), U.S. Pat. No. 4,604,633, Kimura, et al. uses an electrostatic capacity detector to detect the displacement of a flexible bag with respect to a plate affixed to the bottom of a container. The bag acts as a second plate. Because capacitance depends on the area of the plates, the capacitance measurement decreases as the area of the ink bag near the bottom plate decreases. In the Kimura arrangement, the area of the second plate only goes down towards the end of life of the ink bag. In both cases, the presence of "low ink" is detected. While accurate, this is no comfort to the user having a time critical deadline to meet. If this user had been able to gauge the remaining ink, the need for a new ink container would have been anticipated.